Pseudo-Biological Highly Performance Transparent Electrodes Based on Capillary Force-Welded Hybrid AgNW Network

Abstract

Graphene/silver nanowire composite films have great potential as transparent conductive electrodes in the field of optoelectronic devices. So far, antioxidant and reducing the junction resistance are two major parameters in the silver nanowire electrode studies. In this paper, a pseudo-biological inspired structure for transparent electrodes was proposed by combining hybrid diameters silver nanowire network with the chemical vapor deposition-grown (CVD-grown) graphene as a passivation layer. Compared with the traditional structure, the silver nanowire network with this novel structure of human vascular tissue network greatly reduced the sheet resistance. An environmentally friendly liquid, deionized water, was selected for the generation of capillary forces at the liquid bridge, thereby improving the wire junction problem. After welding with the capillary force, the increase in the value of the figure of merit (FoM = σ DC σ OP) acted a pivotal part in improving conductivity with excellent optical performance. In addition, graphene was chosen as an encapsulation layer to protecting silver nanowires from oxidation while improving electrical properties. Compared with the silver nanowire films with a diameter of 20 nm, the σ DC σ OP of the graphene/silver nanowire composite film increased by 69.6 % with a sheet resistance of 26.4 /sq. More importantly, graphene is supposed to protect silver nanowires from oxidation and moisture, which makes the composite films promising as electrodes for underwater optoelectronic devices or a possible development in high humidity environments. INDEX TERMS Capillary force welding, graphene, hybrid diameters silver nanowire network, pseudo-biological structure.

Origin of Capillary-Force-Induced Welding in Ag Nanowires and Ag Nanowire/Carbon Nanotube Conductive Networks

“…Because of their intrinsically high aspect ratio, high conductivity, superior optical transparency, and excellent flexibility, one-dimensional (1D) silver nanowires (AgNWs) have been extensively fabricated as flexible transparent electrodes for the development of next-generation soft wearable electronics. − The electrical percolation of an AgNW network, on the other hand, is heavily dependent on the effective point contact at NW–NW junctions. − The contact resistance ( R c ) at the NW–NW junction, according to Hu and colleagues, can reach 1 GΩ, which is substantially greater than the intrinsic resistance of AgNWs (260–320 Ω) . To substantially decrease R c at junctions, AgNW-based electrodes are usually post-treated with a variety of “welding” techniques, including mechanical pressing, thermal welding, plasmonic welding, chemical welding, , additives soldering, and capillary-force-induced welding, − to form a compact metallic conductive network . Contrary to other techniques that require harsh conditions like destructive high temperatures, devastating pressures, or expensive apparatus, capillary-force-induced welding is a simple, rapid, room-temperature, self-limited nanowelding process. − It has attracted great attention for reducing the R c in AgNW percolative networks since it can provide GPa-level pressure between two adjacent NWs. − During a typical process, distributed water droplets are introduced into the nanostructures of AgNWs, and the capillary force ( F ) is induced during the drying step, effectively welding the junctions to minimize the R c . − According to Liu et al, after capillary welding, the sheet resistance ( R s ) of a AgNW conductive film with an average diameter of 90 nm dramatically decreased from 2.25 × 10 5 to 179 Ω sq.…”

“…To substantially decrease R c at junctions, AgNW-based electrodes are usually post-treated with a variety of “welding” techniques, including mechanical pressing, thermal welding, plasmonic welding, chemical welding, , additives soldering, and capillary-force-induced welding, − to form a compact metallic conductive network . Contrary to other techniques that require harsh conditions like destructive high temperatures, devastating pressures, or expensive apparatus, capillary-force-induced welding is a simple, rapid, room-temperature, self-limited nanowelding process. − It has attracted great attention for reducing the R c in AgNW percolative networks since it can provide GPa-level pressure between two adjacent NWs. − During a typical process, distributed water droplets are introduced into the nanostructures of AgNWs, and the capillary force ( F ) is induced during the drying step, effectively welding the junctions to minimize the R c . − According to Liu et al, after capillary welding, the sheet resistance ( R s ) of a AgNW conductive film with an average diameter of 90 nm dramatically decreased from 2.25 × 10 5 to 179 Ω sq. –1 .…”

“…A simplified model of two spherical surfaces connected by a liquid bridge has been proposed by several groups to measure the capillary force associated with the AgNWs. − The model predicts that the capillary force between the two spherical particles (the equivalent of AgNWs) can increase by up to 23.0 nN as the particles approach . However, the proposed sphere–sphere model in the aforementioned reports is only applicable to spheres of the same radius, which is attributed to the fact that all the researchers used the concept of immersion height (the critical factor that represents the size of the liquid bridge) and assumed that the immersion height of the two spheres in the liquid bridge was the same.…”

Distribution Density-Aware Compensation for High-Resolution Stretchable Display

“…Material stretching methods are aimed at developing devices that are stable, flexible, and self-stretchable without structural deformation. Typical flexible devices include stretchable transparent electrodes [22]- [25], thin-film transistors [26], [27], and LEDs [28]- [30]. Stretchable transparent electrodes consist of a nanowire transparent device with high conductivity and elasticity.…”

Scalable Solution-Processed Fabrication Approach for High-Performance Silver Nanowire/MXene Hybrid Transparent Conductive Films

“…Tang et al reported that solution-processed MXene/AgNW-PUA transparent electrodes were used for flexible organic solar cells [ 28 ]. This method of directly covering MXene and graphene on the silver nanowire network cannot effectively solve the wire junction problem, it requires additional welding steps which limited the large-scale applications usually [ 29 , 30 ]. Therefore, it is urgently needed to prepare high-performance TCFs by adjusting the structures, composition, and preparation methods.…”